Electric switch



May 23, 1944,

w., M. JOHNSON ELECTRIC SWITCH Filed June 1, 1942 Ihvnfio: WiLbeV` M.Johnson,

His Arcbomeg.

Patented May 23, 1944 ELECTRIC SWITCH Wilber M. Johnson, ClevelandHeights, Ohio, assignor to General Electric Company, a corporation ofNew York Application June 1, 1942, Serl No. 445,530

3 Claims. ('Cl. 20G-152) My invention relates to fluid ilow electricswitchesof the type comprising a pair of cuplike, electricallyconducting, metal members electrically insulated from and hermeticallysealed to one another by a relatively thin ring of glass to form anenclosure for a quantity o :l conducting iluid, such as mercury. In theusual form of such switches a barrier of arc resisting, electricallyinsulating material is disposed between the metal members to divide theinterior of the switch into chambers. The chambers are connected by anaperture in the barrier through which the mercury flows to electricallyconnect the metal members in the circuit making position of the switch.The switch is mounted with the glass ring in a vertical plane and ismoved from a circuit making to a circuit breaking position by rotatingthe switch in said plane to raise the aperture above the level of themercury thus interrupting the conducting path between the metal members.

. secured hereto and enclosing a reiiector pro- An object of myinvention is to provide a switch of the above type which may be mountedwith the glass ring in a horizontal plane to close the electricallyconducting path in the switch and which is moved from a closed circuitposition to an opencircuit position by tilting the switch at an angle tothe horizontal. Another object oi my invention is to provide such aswitchV in which the maximum angle to the horizontalto which the switchmay be tilted without breaking the' conducting path between the metalmembers may be selected to suit the intended use of the switch. Anotherobject o my invention is to provide such a switch which is useful inelectric lamps of the portable, self-contained, battery operated typecommonly known as flashlights to automatically extinguish the lamp inpredetermined positions g thereof. Another object of my invention is toprovide a .iiashlight switch for Vcontrolling the flow of current in thecircuit of the flashlight whereby the latter can project only ahorizontally or downwardly directed beam of light. A further object ofmy invention is to provide such a switch of simple structure readilyincorporated into and removed from commercially available flashlightsand other electrical apparatus without changing the structure orarrangement of the component parts thereof. 1 A

Further objects and advantages of my invention will appear from thefollowing detailed description of species thereof and from theaccompanying drawing, in which Fig. 1 is a side elevational, partlysectional view of a commercially available flashlight showing a speciesof switch embodying my invention incorporated therein; u

vided with a socket for supporting an incandescent lamp in the usualmanner. An elongated electric storage battery t6 of conventional typehaving two terminals isheld in said casing il by the clamping action ofthe screw caps l2 and Il and the spring I3. The electrical circuitincluding the battery i6 and the incandescent lamp may be made andbroken by the manually operated switch i'l and-also includes.the springt3 and the casing l l. The flashlight projects a beam of light coaxialwith the casing li. Further description of the structural details andoperation of the flashlight Ill is deemed unnecessary since y these arewell known.

A mercury switch I8 is disposed between spring I3 and the battery IG ofthe ilashlight illustrated in Fig. 1. The switch I8 is in its circuitmaking position when the beam projected by the flashlight is directedvertically downward. In accordance with my invention the switch I8 maybe so constructed and arranged that it is not moved from its circuitmaking to its circuit breaking position until the axis of the downwardlyprojected beam is directed beyond a predetermined angle to the vertical.This angle may be selected as desired up to and including ninety degreesto the vertical which would be horizontal.` Thus, the beam may bedirected at angles smaller than the predetermined angle but cannot beinad-r vertently directed upward beyond the selected angle. This isadvantageous in many locations, such as in theaters or the like.

Inv Fig. 2 of the drawing I have shown in its circuit making position aspecies of switch I8 useful in the ilashlight illustrated in Fig. 1. The

switch I8 comprises a pair of cup-shaped or dished metal members I9 and20 so shaped and juxtaposed as to form an enclosed space between them.These members I! and 20 have ilanges 2| and 22, respectively, and arespaced from one another by an annular spacer 23 having a peripheralportion 24 interposed between said flanges 2l and 22. Said spacer 23consists of electrically insulating material, which may be magnesio. oralumina. The annular groove or slot formed by the portion 24 and theilanges 2| and 22 is filled with a ring 26 of glass or similarthermoplastic material which is fused to ilanges 2| and 22 to form ahermetically tight, mechanically strong joint therebetween. The switchI3 contains a quantity of mercury 23, or equivalent material, andpreferably is lled with a gas, such as hydrogen, at substantial pressurethrough the opening 21 in said member I3 during manufacture. The opening21 is hermetically sealed by fusion welding a metal closure member 23therein. Similar switches in which a perforated barrier is disposedbetween the members I3 and20 instead of the annular spacer 23 of myinvention are described in the U. S. Patents 2,101,092, issued December7, 1937, and 2,175,306, issued October 10, 1939.

'I'he inner surface 29 of the annular spacer 23 has a frusto-conicalshape. The reentrant portion 30 of the member I9 and the reentrantportion 3I of the member 20 are contiguous with said surface 29. Thespacer 23 engages the members I3 and 20 over a substantial area tostrengthen the switch against forces tending to press said members I3and 20 together. A metal Wire 32 is secured, as by welding, to saidreentrant portion 3D and terminates adjacent the reentrant portion 3I.In the circuit making position of the switch Il, shown in Figs. 1 and 2,the mercury 26 bridges the gap between the end of wire 32 andthe innersurface of portion 3l. The ring 25 is then in a horizontal plane.Circuit interruption takes place when the switch is tilted so that themercury 26 does not bridge this gap or the gap between the inner surfaceof the reentrant portion 3i and the reentrant portion 33. The maximumangle to the horizontal to which the switch I8 may be tilted withoutcausing circuit interruption is determined by the relation between thequantity of mercury 26, the size of these gaps and the slope of theinner surface of spacer 23. If, for example, the said inner surface isof cylindrical shape and the quantity of mercury 26 together with theaforesaid gap is properly selected, then the said maximum angle may beas great as 90 to the horizontal. Of course, the maximum angle of tiltmay be changed as desired to suit the needs of the user. In the switchillustrated in Fig. 2, the said maximum angle is considerably less than90.

The switch illustrated in Fig. 3 of the drawing is similar to thatdescribed above and shown in Fig. 2. In this embodiment, however, thelower wall member 33 is in the forml of a dish having a sloping surface34 and a rounded reentrant portion 35. The closure member 2B is in saidportion 35. The lower end portion of the wire 32 is in the form of aring 36 disposed in the annular space between the surface 3| and therounded portion 33 and is spaced from the inner surface of the member33. The mercury 26 bridges the gap between the ring 36 and the member 33in the circuit making position of the switch. The lower surface of thespacer 23 in this embodiment is in a plane including the upper surfaceof the member 33 and extends inwardly to form a stop or shoulder tolimit the movement ofthe mercury 26 when the switch is tilted. Thus, themercury 26 cannot bridge the members I3 and 33 when the switch istilted. As in the embodiment illustrated in Fig.

.Q the slope of the surface 34, the quantity of mercury 23 and the sizeof the gap between the ring 33 and the inner surface of the member 33determine the maximum angle to the horizontal to which the switch may betilted without interrupting the circuit in which it is included. In thisembodiment the said maximum angle is also less than to the horizontal.

Thelswitches illustrated in Figs. 2 and 3 are readllyincorpbrated intoand removed from the ilashlight illustrated in Fig. 1 by removing thecap l2 of the flashlight, inserting the switch in proper positionagainst the battery I3 and replacing the cap I2. The switch is engagedand heldin proper position by the spring I3 in the reentrant portion33o! the member I3. The dlil'erent conilguration of the wall members I3,2II and 33 facilitates mounting of the switches in proper position inthe flashlight particularly in the dark when the sense of touch alonecan be used. The position of the switch may be reversed when an upwardbeam is desired. The switches of Figs. 1 and 2 may be disposed in theliashlight between the battery I6 and the center contact of the lampbase, when desired.

It will be understood, of course, that I contemplate the use of myimproved iiuid ilow switch in other types of flashlights and electricalapparatus. For example, ashlights projecting a beam of light having anaxis normal to the longitudinal axis oi the battery enclosing part ofthe flashlight are well known in commerce. In such flashlights theswitch is effectively disposed between the center contact of the lampbase and the battery with the plane or the glass ring normal to the beamaxis.

What I claim as new and desire toA secure by Letters Patent of theUnited States is:

l. An electric, uid flow switch comprising spaced, shallow, dish-shaped,electrically conducting wall members having substantially planar,parallel, peripheral portions hermetically joined by a thin ring ofelectrically insulating material to form an enclosure of substantiallygreater diameter than depth, an electrically insulating annular spacerin said enclosure engag- `ing said wall members and having an openingsubstantially smaller in diameter than that of said enclosure anddefining, with said wall members, a cavity in said switch, a solidcontact member supported in said cavity by one of said wall members andterminating adjacent the other of said wall members, and suilicientmercury in said cavity to bridge the space between said contact memberand the adjacent wall member in one position of said switch, thecavity-defining surface of said spacer providing a path for mercury flowof greater length than the distance between the peripheral portions ofsaid wall members and of suiiicient length with respect to the quantityof said mercury to prevent said mercury bridging the space between saidwall members in any position of said switch.

2. An electric, fluid flow switch comprising spaced, shallow,dish-shaped, electrically conducting wall members having substantiallyplanar, parallel, peripheral portions hermetically joined by a thin ringof electrically insulating material to form an enclosure ofsubstantially greater diameter than depth, an electrically insulatingannular spacer in said enclosure engaging said wall members and havingan opening substantially smaller in diameter than that of said enclosureand defining, with said wa11 members, a cavity in said switch. a solidcontact member supported in said cavity by one of said wall members andterminating adjacent the other of said wall members, and sumcientmercury in said bers and of sufcient length with respect to the quantityof said mercury to prevent said mercury bridging the space between saidwall members in any position of said switch.

3. A mercury switch comprising a pair of opposed metal discs spaced ashort distance apart, an annular spacer of insulating material fillingthe space between said discs except for the central opening in saidannular spacer, said opening being tapered so as to define afrustro-conical cavity bounded at its ends by center portions of saiddiscs, a contact secured to the center portion of the disc dening thelarger base of the cavity and extending axially of the cavity to withina short distance of the center portion of that disc which denes thesmaller base of the cavity, and a quantity of mercury in said cavitysuillciently large to bridge the gap between said contact and the saiddisc which defines the smaller base when said smaller base is 1owermostand horizontal, said quantity of mercury being insufficient to bridgethe space between the said center portions of the discs in any positionof the switch.

WILBER M JOHNSON.

